Cadbury also campained against alcohol, and he led a campaign to ban the use of child labour for sweeping chimneys and campaigned against animal cruelty, forming the Animals Friend Society, a forerunner of the Royal Society for the Prevention of Cruelty to Animals.

As a Quaker in the early 19th century, he was not allowed to enter a university, so could not pursue a profession such as medicine or law. As Quakers are pacifist, a military career was also out of the question. So, like many other Quakers of the time, he turned his energies toward business and began an apprenticeship as a tea dealer in Leeds in 1818.

Returning to Birmingham in 1824, Cadbury opened a small one-man grocery shop at 93 Bull Street. In 1831, he switched his business and rented a small factory (an old malthouse) in Crooked Lane to begin the manufacture of drinking chocolate and cocoa.

Cadbury was influenced in his choice of trade by his temperance beliefs – he felt alcohol was a major cause of poverty and other social ills, and saw cocoa and chocolate as alternatives. As a social reformer, he also led a campaign to ban the use of child labour for sweeping chimneys and campaigned against animal cruelty, forming the Animals Friend Society, a forerunner of the Royal Society for the Prevention of Cruelty to Animals.

Meanwhile, Cadbury’s manufacturing enterprise prospered, his brother Benjamin Head Cadbury joined the business in 1847 and they rented a larger factory on Bridge Street. Two years later, in 1849, the Cadbury brothers pulled out of the retail business, leaving it in the hands of John’s son , Richard Cadbury Barrow. (Barrow’s remained a leading Birmingham store until the 1960s.)

Cadbury married twice. He married Priscilla Ann Dymond (1799–1828), in 1826, but she died two years later. In 1832 he married his second wife, Candia Barrow (1805–1855) and had seven children: John (1834–1866), Richard (1835–1899), Maria (1838–1908), George (1839–1922), Joseph (1841–1841), Edward (1843–1866), and Henry (1845–1875).

Benjamin Head Cadbury and John Cadbury dissolved their partnership in 1860. John retired in 1861 due to the death of his wife, and his sons Richard and George succeeded him in the business.

In 1879 they relocated to an area of what was then north Worcestershire, on the borders of the parishes of Northfield and King’s Norton centred on the Georgian built Bournbrook Hall, where they developed the garden village of Bournville; now a major suburb of Birmingham.

The family developed the Cadbury’s factory, which remains a key site of Cadbury. The district around the factory has been ‘dry’ for over 100 years, with no alcohol being sold in pubs, bars or shops. Residents have fought to maintain this, winning a court battle in March 2007 with Britain’s biggest supermarket chain Tesco, to prevent it selling alcohol in its local outlet.

For the remainder of his life, John Cadbury engaged in civic and social work in Birmingham.

Together with his younger brother George he took over the family business in 1861 and in 1878 they acquired 14 acres (57,000 m²) of land in open country, four miles (6 km) south of Birmingham where they opened a new factory in 1879. Over the following years, more land was acquired and a model village was built for his workers which became known as Bournville.